Commit 833d8469 authored by Glauber de Oliveira Costa's avatar Glauber de Oliveira Costa Committed by Ingo Molnar
Browse files

x86: unify smp parts of system.h 



The memory barrier parts of system.h are not very different between
i386 and x86_64, the main difference being the availability of
instructions, which we handle with the use of ifdefs.

They are consolidated in system.h file, and then removed from
the arch-specific headers.

Signed-off-by: default avatarGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 62fe164c

include/asm-x86/system.h

+105 −0
Original line number Diff line number Diff line
@@ -202,4 +202,109 @@ extern void free_init_pages(char *what, unsigned long begin, unsigned long end); 


void default_idle(void);



/*

 * Force strict CPU ordering.

 * And yes, this is required on UP too when we're talking

 * to devices.

 */

#ifdef CONFIG_X86_32

/*

 * For now, "wmb()" doesn't actually do anything, as all

 * Intel CPU's follow what Intel calls a *Processor Order*,

 * in which all writes are seen in the program order even

 * outside the CPU.

 *

 * I expect future Intel CPU's to have a weaker ordering,

 * but I'd also expect them to finally get their act together

 * and add some real memory barriers if so.

 *

 * Some non intel clones support out of order store. wmb() ceases to be a

 * nop for these.

 */

#define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)

#define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)

#define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)

#else

#define mb() 	asm volatile("mfence":::"memory")

#define rmb()	asm volatile("lfence":::"memory")

#define wmb()	asm volatile("sfence" ::: "memory")

#endif



/**

 * read_barrier_depends - Flush all pending reads that subsequents reads

 * depend on.

 *

 * No data-dependent reads from memory-like regions are ever reordered

 * over this barrier.  All reads preceding this primitive are guaranteed

 * to access memory (but not necessarily other CPUs' caches) before any

 * reads following this primitive that depend on the data return by

 * any of the preceding reads.  This primitive is much lighter weight than

 * rmb() on most CPUs, and is never heavier weight than is

 * rmb().

 *

 * These ordering constraints are respected by both the local CPU

 * and the compiler.

 *

 * Ordering is not guaranteed by anything other than these primitives,

 * not even by data dependencies.  See the documentation for

 * memory_barrier() for examples and URLs to more information.

 *

 * For example, the following code would force ordering (the initial

 * value of "a" is zero, "b" is one, and "p" is "&a"):

 *

 * <programlisting>

 *	CPU 0				CPU 1

 *

 *	b = 2;

 *	memory_barrier();

 *	p = &b;				q = p;

 *					read_barrier_depends();

 *					d = *q;

 * </programlisting>

 *

 * because the read of "*q" depends on the read of "p" and these

 * two reads are separated by a read_barrier_depends().  However,

 * the following code, with the same initial values for "a" and "b":

 *

 * <programlisting>

 *	CPU 0				CPU 1

 *

 *	a = 2;

 *	memory_barrier();

 *	b = 3;				y = b;

 *					read_barrier_depends();

 *					x = a;

 * </programlisting>

 *

 * does not enforce ordering, since there is no data dependency between

 * the read of "a" and the read of "b".  Therefore, on some CPUs, such

 * as Alpha, "y" could be set to 3 and "x" to 0.  Use rmb()

 * in cases like this where there are no data dependencies.

 **/



#define read_barrier_depends()	do { } while (0)



#ifdef CONFIG_SMP

#define smp_mb()	mb()

#ifdef CONFIG_X86_PPRO_FENCE

# define smp_rmb()	rmb()

#else

# define smp_rmb()	barrier()

#endif

#ifdef CONFIG_X86_OOSTORE

# define smp_wmb() 	wmb()

#else

# define smp_wmb()	barrier()

#endif

#define smp_read_barrier_depends()	read_barrier_depends()

#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)

#else

#define smp_mb()	barrier()

#define smp_rmb()	barrier()

#define smp_wmb()	barrier()

#define smp_read_barrier_depends()	do { } while (0)

#define set_mb(var, value) do { var = value; barrier(); } while (0)

#endif





#endif

include/asm-x86/system_32.h

+0 −99
Original line number Diff line number Diff line
@@ -36,105 +36,6 @@ extern struct task_struct * FASTCALL(__switch_to(struct task_struct *prev, struc 
#endif	/* __KERNEL__ */





/*

 * Force strict CPU ordering.

 * And yes, this is required on UP too when we're talking

 * to devices.

 *

 * For now, "wmb()" doesn't actually do anything, as all

 * Intel CPU's follow what Intel calls a *Processor Order*,

 * in which all writes are seen in the program order even

 * outside the CPU.

 *

 * I expect future Intel CPU's to have a weaker ordering,

 * but I'd also expect them to finally get their act together

 * and add some real memory barriers if so.

 *

 * Some non intel clones support out of order store. wmb() ceases to be a

 * nop for these.

 */

 



#define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)

#define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)

#define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)



/**

 * read_barrier_depends - Flush all pending reads that subsequents reads

 * depend on.

 *

 * No data-dependent reads from memory-like regions are ever reordered

 * over this barrier.  All reads preceding this primitive are guaranteed

 * to access memory (but not necessarily other CPUs' caches) before any

 * reads following this primitive that depend on the data return by

 * any of the preceding reads.  This primitive is much lighter weight than

 * rmb() on most CPUs, and is never heavier weight than is

 * rmb().

 *

 * These ordering constraints are respected by both the local CPU

 * and the compiler.

 *

 * Ordering is not guaranteed by anything other than these primitives,

 * not even by data dependencies.  See the documentation for

 * memory_barrier() for examples and URLs to more information.

 *

 * For example, the following code would force ordering (the initial

 * value of "a" is zero, "b" is one, and "p" is "&a"):

 *

 * <programlisting>

 *	CPU 0				CPU 1

 *

 *	b = 2;

 *	memory_barrier();

 *	p = &b;				q = p;

 *					read_barrier_depends();

 *					d = *q;

 * </programlisting>

 *

 * because the read of "*q" depends on the read of "p" and these

 * two reads are separated by a read_barrier_depends().  However,

 * the following code, with the same initial values for "a" and "b":

 *

 * <programlisting>

 *	CPU 0				CPU 1

 *

 *	a = 2;

 *	memory_barrier();

 *	b = 3;				y = b;

 *					read_barrier_depends();

 *					x = a;

 * </programlisting>

 *

 * does not enforce ordering, since there is no data dependency between

 * the read of "a" and the read of "b".  Therefore, on some CPUs, such

 * as Alpha, "y" could be set to 3 and "x" to 0.  Use rmb()

 * in cases like this where there are no data dependencies.

 **/



#define read_barrier_depends()	do { } while(0)



#ifdef CONFIG_SMP

#define smp_mb()	mb()

#ifdef CONFIG_X86_PPRO_FENCE

# define smp_rmb()	rmb()

#else

# define smp_rmb()	barrier()

#endif

#ifdef CONFIG_X86_OOSTORE

# define smp_wmb() 	wmb()

#else

# define smp_wmb()	barrier()

#endif

#define smp_read_barrier_depends()	read_barrier_depends()

#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)

#else

#define smp_mb()	barrier()

#define smp_rmb()	barrier()

#define smp_wmb()	barrier()

#define smp_read_barrier_depends()	do { } while(0)

#define set_mb(var, value) do { var = value; barrier(); } while (0)

#endif



#include <linux/irqflags.h>



/*

include/asm-x86/system_64.h

+0 −25
Original line number Diff line number Diff line
@@ -48,31 +48,6 @@ 
    

#endif	/* __KERNEL__ */



#ifdef CONFIG_SMP

#define smp_mb()	mb()

#define smp_rmb()	barrier()

#define smp_wmb()	barrier()

#define smp_read_barrier_depends()	do {} while(0)

#else

#define smp_mb()	barrier()

#define smp_rmb()	barrier()

#define smp_wmb()	barrier()

#define smp_read_barrier_depends()	do {} while(0)

#endif



    

/*

 * Force strict CPU ordering.

 * And yes, this is required on UP too when we're talking

 * to devices.

 */

#define mb() 	asm volatile("mfence":::"memory")

#define rmb()	asm volatile("lfence":::"memory")

#define wmb()	asm volatile("sfence" ::: "memory")



#define read_barrier_depends()	do {} while(0)

#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)



static inline unsigned long read_cr8(void)

{

	unsigned long cr8;

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